Eddy current heat generating apparatus

ABSTRACT

The disclosed heat generating apparatus includes: a rotary shaft, a heat generator, a plurality of permanent magnets, a magnet holder, and a heat recovery system. The rotary shaft is rotatably supported by a non-rotative body. The heat generator is fixed to the rotary shaft. The magnets are arrayed to face the heat generator with a gap such that magnetic pole arrangements of adjacent ones of the magnets are opposite to each other. The magnet holder holds the magnets and is fixed to the body. The heat recovery system collects heat generated in the heat generator.

TECHNICAL FIELD

The present invention relates to a heat generating apparatus thatrecovers thermal energy from kinetic energy of a rotary shaft, and moreparticularly to an eddy current heat generating apparatus employingpermanent magnets (hereinafter referred to simply as “magnets”) andutilizing eddy currents generated by the effects of magnetic fields fromthe magnets.

BACKGROUND ART

In recent years, generation of carbon dioxide accompanying burning offossil fuels is acknowledged as a problem. Therefore, utilization ofnatural energy, such as solar thermal energy, wind energy, hydro-energyand the like, is promoted. Among the natural energy, wind energy andhydro-energy are kinetic energy of a fluid. Conventionally, electricpower has been generated from kinetic energy of a fluid.

For example, in a typical wind electric generating facility, a propellerreceives wind and thereby rotates. The rotary shaft of the propeller isconnected to the input shaft of a power generator, and along with therotation of the propeller, the input shaft of the power generatorrotates. Thereby, electric power is generated in the power generator. Inshort, in a typical wind electric generating facility, wind energy isconverted to kinetic energy of the rotary shaft of a propeller, and thekinetic energy of the rotary shaft is converted to electric energy.

Japanese Patent Application Publication No. 2011-89492 (PatentLiterature 1) suggests a wind electric generating facility with improvedenergy use efficiency. The electric generating facility disclosed inPatent Literature 1 includes a heat generator (retarder 30 in PatentLiterature 1) that generates thermal energy in the process of convertingwind energy to electric energy.

In the wind electric generating facility disclosed in Patent Literature1, wind energy is converted to kinetic energy of the rotary shaft of apropeller, and the kinetic energy of the propeller is converted tohydraulic energy of a hydraulic pump. The hydraulic energy rotates ahydraulic motor. The spindle of the hydraulic motor is connected to therotary shaft of the heat generator, and the rotary shaft of the heatgenerator is connected to the input shaft of a power generator. Alongwith rotation of the hydraulic motor, the rotary shaft of the heatgenerator rotates, and the input shaft of the power generator rotates,whereby electricity is generated in the power generator.

The heat generator utilizes eddy currents generated by the effects ofmagnetic fields from permanent magnets to reduce the rotational speed ofthe rotary shaft of the heat generator. Accordingly, the rotationalspeed of the spindle of the hydraulic motor is reduced, and therotational speed of the propeller is adjusted via the hydraulic pump.

In the heat generator, the generation of eddy currents leads togeneration of braking force to reduce the rotational speed of the rotaryshaft of the heat generator, and generation of heat as well. Thus, apart of wind energy is converted to thermal energy. According to PatentLiterature 1, the heat (thermal energy) is collected in a heat storagedevice, and the motor is driven by the collected thermal energy, wherebythe power generator is driven. Consequently, electricity is generated inthe power generator.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Publication No.2011-89492

SUMMARY OF INVENTION Technical Problems

The wind electric generating facility disclosed in Patent Literature 1includes a hydraulic pump and a hydraulic motor between a propeller thatis a rotary shaft and a heat generator. Thus, the structure of thefacility is complicated. Also, multistage energy conversion isnecessary, and a large energy loss is caused during the energyconversion. Accordingly, the thermal energy obtained in the heatgenerator is small.

In the heat generator disclosed in Patent Literature 1, a plurality ofmagnets are circumferentially arrayed to face the whole circumference ofthe inner peripheral surface of a cylindrical rotor. The magnetic poles(the north pole and the south pole) of each of the magnets arecircumferentially arranged, and the magnetic pole arrangements ofadjacent ones of the circumferentially arrayed magnets are the same.Therefore, the magnetic fields of the magnets do not spread, and themagnetic flux density reaching the rotor is low. Then, the eddy currentsgenerated in the rotor by the effects of magnetic fields from themagnets are low, and it is not possible to achieve sufficient heatgeneration.

The present invention has been made in view of the current situation. Anobject of the present invention is to provide an eddy current heatgenerating apparatus that is capable of efficiently recovering thermalenergy from kinetic energy of a rotary shaft.

An eddy current heat generating apparatus according to an embodiment ofthe present invention includes:

a rotary shaft rotatably supported by a non-rotative member;

a heat generator fixed to the rotary shaft;

a plurality of permanent magnets arrayed to face the heat generator witha gap such that magnetic pole arrangements of adjacent ones of thepermanent magnets are opposite to each other;

a magnet holder holding the permanent magnets and fixed to thenon-rotative member; and

a heat recovery system collecting heat generated in the heat generator.

Advantageous Effects of Invention

In the eddy current heat generating apparatus according to the presentinvention, the magnetic pole arrangements of adjacent ones of themagnets arrayed to face the heat generator are opposite to each other.Accordingly, the magnetic fields of the magnets spread out, and themagnetic flux density reaching the heat generator becomes high.Accordingly, the eddy currents generated in the heat generator by theeffects of magnetic fields from the magnets become high, therebyallowing for a sufficient amount of heat generation. Thus, according tothe present invention, thermal energy can be recovered from the kineticenergy of the rotary shaft efficiently.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a longitudinal sectional view of a heat generatingapparatus according to a first embodiment.

[FIG. 2] FIG. 2 is a cross-sectional view of the heat generatingapparatus according to the first embodiment.

[FIG. 3] FIG. 3 is a cross-sectional view of a preferred example of aheat generator of the heat generating apparatus according to the firstembodiment.

[FIG. 4] FIG. 4 is a cross-sectional view of a heat generating apparatusaccording to a second embodiment.

[FIG. 5] FIG. 5 is a longitudinal sectional view of a heat generatingapparatus according to a third embodiment.

[FIG. 6] FIG. 6 is a longitudinal sectional view of a heat generatingapparatus according to a fourth embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will hereinafter be described. Inthe following, the embodiments of the present invention will bedescribed with some examples given. However, the present invention isnot limited to the examples that will be given below. In the following,specific values and materials may be presented as examples, but othervalues and materials may be used as long as the use of those values andmaterials provides the effect of the present invention.

An eddy current heat generating apparatus according to an embodiment ofthe present invention includes a rotary shaft, a heat generator, aplurality of permanent magnets, a magnet holder, and a heat recoverysystem. The rotary shaft is rotatably supported by a non-rotativemember. The heat generator is fixed to the rotary shaft. The pluralityof permanent magnets are arrayed to face the heat generator with a gapsuch that the magnetic pole arrangements of adjacent ones of the magnetsare opposite to each other. The magnet holder holds the permanentmagnets, and is fixed to the non-rotative member. The heat recoverysystem collects heat generated in the heat generator.

At least a part of the heat generator is made of a material that causeselectromagnetic induction (specifically, a conductive material). It ispreferred that at least the portion of the heat generator adjacent tothe magnets is made of such a material that causes electromagneticinduction. Specific examples of the material for the heat generator willbe given later.

In the eddy current heat generating apparatus according to the presentembodiment, since the magnetic pole arrangements of adjacent ones of themagnets arrayed to face the heat generator are opposite to each other,the magnetic fields of the magnets spread out, and the magnetic fluxdensity reaching the heat generator is high. Accordingly, high eddycurrents are generated by the effects of magnetic fields from themagnets, and sufficient heat generation can be achieved. Thus, it ispossible to recover thermal energy from kinetic energy of the rotaryshaft efficiently.

In the heat generating apparatus, the heat recovery system may include aclosed container, pipes, a heat storage device, and a heat medium. Theclosed container is fixed to the non-rotative member and surrounds theheat generator, and the closed container has a non-magnetic partitionwall disposed in the gap between the heat generator and the permanentmagnets. The pipes are connected to an inlet and an outlet,respectively, leading to the internal space of the closed container. Theheat storage device is connected to the pipes. The heat mediumcirculates in the closed container, the pipes and the heat storagedevice.

There are no special limitations to the heat storage device, and a knownheat storage device where thermal energy carried by the heat medium canbe stored is usable. There are no special limitations to the heatmedium, and a known heat medium is usable. The heat medium may be, forexample, molten salt of a nitrate-based material (for example, mixedsalt of sodium nitrate: 60% and potassium nitrate: 40%). Alternatively,heat medium oil, water (steam), air, supercritical CO₂ or the like maybe used.

The partition wall is preferably made of a non-magnetic material so asnot to block the magnetic fluxes from the magnets from reaching the heatgenerator. Examples of materials usable for the partition wall includealuminum alloys, austenite stainless steel, copper alloys, high heatresistance resin and ceramics. The surface of the partition wall facingthe heat generator may be a mirror surface with high smoothness. Thisreduces heat transfer from the heat generator to the magnets.

In this case, it is preferred that the space between the heat generatorand the partition wall is filled with a heat insulating material oralternatively is made vacuum.

The heat generating apparatus may be an apparatus that recovers thermalenergy from kinetic energy of the rotary shaft rotated by kinetic energyof a fluid. The kinetic energy of a fluid includes natural energy suchas wind power and hydraulic power. Kinetic energy obtained from naturalenergy is variable, but the heat generating apparatus can recoverthermal energy even from such variable kinetic energy without decreasingthe efficiency very much.

It is preferred that the heat generating apparatus further includes acooling system for cooling the permanent magnets.

In the heat generating apparatus, the heat generator may be cylindrical,and the permanent magnets may be circumferentially arrayed to face thewhole circumference of the outer peripheral surface of the heatgenerator such that the magnetic poles of each of the magnets areradially arranged and such that the magnetic pole arrangements ofadjacent ones of the circumferentially arrayed magnets are opposite toeach other. In this case, the magnet holder preferably includes acylindrical member holding the permanent magnets on its inner peripheralsurface, and the cylindrical member is preferably ferromagnetic.Examples of such ferromagnetic materials usable for the magnet holderinclude ferromagnetic metal materials (for example, carbon steel, castiron and the like).

In the heat generating apparatus, the heat generator may be cylindrical,and the permanent magnets may be circumferentially arrayed to face thewhole circumference of the outer peripheral surface of the heatgenerator such that the magnetic poles of each of the magnets arecircumferentially arranged and such that the magnetic pole arrangementsof adjacent ones of the circumferentially arrayed magnets are oppositeto each other. In this case, the magnet holder preferably includes acylindrical member holding the permanent magnets on its inner peripheralsurface, and the cylindrical member is preferably non-magnetic. Further,it is preferred that pole pieces are provided between thecircumferentially arrayed magnets. Examples of such non-magneticmaterials usable for the magnet holder include non-magnetic metalmaterials (for example, aluminum alloys, austenitic stainless steel,copper alloys and the like).

In the heat generating apparatus, the heat generator may be cylindrical,and the permanent magnets may be axially arrayed to face the whole axiallength of the outer peripheral surface of the heat generator such thatthe magnetic poles of each of the magnets are axially arranged and suchthat the magnetic pole arrangements of adjacent ones of the axiallyarrayed magnets are opposite to each other. In this case, the magnetholder preferably includes a cylindrical member holding the permanentmagnets on its inner peripheral surface, and the cylindrical member ispreferably non-magnetic. Further, it is preferred that pole pieces areprovided between the axially arrayed magnets and at both ends of theaxial array of permanent magnets.

In the heat generating apparatus, the heat generator may be disk-shaped,and the permanent magnets may be circumferentially arrayed to face thewhole circumference of the principal surface of the heat generator suchthat the magnetic poles of each of the magnets are axially arranged andsuch that the magnetic pole arrangements of adjacent ones of thecircumferentially arrayed magnets are opposite to each other. In thiscase, the magnet holder may include a disk-shaped member holding thepermanent magnets on its surface facing the principal surface of theheat generator, and the disk-shaped member may be ferromagnetic.

In the heat generating apparatus, the heat generator may be disk-shaped,and the permanent magnets may be circumferentially arrayed to face thewhole circumference of the principal surface of the heat generator suchthat the magnetic poles of each of the magnets are circumferentiallyarrayed and such that the magnetic pole arrangements of adjacent ones ofthe circumferentially arrayed magnets are opposite to each other. Inthis case, the magnet holder preferably includes a disk-shaped memberholding the permanent magnets on its surface facing the principalsurface of the heat generator, and the disk-shaped member is preferablynon-magnetic. Further, it is preferred that pole pieces are providedbetween the circumferentially arrayed magnets.

In the heat generating apparatus, the heat generator may be disk-shaped,and the permanent magnets may be radially arrayed to face the wholeradius of the principal surface of the heat generator such that themagnetic poles of each of the magnets are radially arranged and suchthat the magnetic pole arrangements of adjacent ones of the radiallyarrayed magnets are opposite to each other. In this case, the magnetholder preferably includes a disk-shaped member holding the permanentmagnets on its surface facing the principal surface of the heatgenerator, and the disk-shaped member is preferably non-magnetic.Further, it is preferred that pole pieces are provided between theradially arrayed magnets and at both ends of the radial array ofpermanent magnets.

The apparatuses of the type including a cylindrical heat generator havesome advantages as follows over the apparatuses of the type including adisk-shaped heat generator. In any of the apparatuses of the formertype, it is easy to keep the relative speed of the heat generator to thepermanent magnets high and constant, and accordingly, the apparatus isexcellent in heat generation efficiency. Also, the apparatuses of theformer type are easy to be reduced in size as compared with theapparatuses of the latter type.

In any of the above-described heat generating apparatuses, the heatgenerator may be made of one or more kinds of conductive magneticmaterials.

In any of the above-described heat generating apparatuses, the heatgenerator may be made of at least a conductive ferromagnetic materialand a conductive non-magnetic material, and the conductive non-magneticmaterial may be disposed close to the permanent magnets. Examples ofsuch ferromagnetic materials include conductive ferromagnetic metalmaterials which will be described later. Examples of such conductivenon-magnetic materials include conductive non-magnetic metal materialswhich will be described later.

Any of the above-described heat generating apparatuses can be mounted inan electric generating facility utilizing kinetic energy of a fluid (forexample, natural energy such as wind energy and hydro-energy), such as awind electric generating facility, a hydroelectric generating facilityor the like. For example, by replacing the power-generating unit in aknown wind electric or hydroelectric generating facility with one of theabove-described heat generating apparatuses, it is possible to generatethermal energy. Accordingly, the structure of a known electricgenerating facility can be applied to the portions other than the heatgenerating apparatus. Also, any of the above-described heat generatingapparatuses can be mounted in a vehicle. In either case, the heatgenerating apparatus recovers thermal energy from kinetic energy of arotary shaft. The recovered thermal energy may be used for generation ofelectric energy.

Eddy current heat generating apparatuses according to some embodimentsof the present invention will hereinafter be described.

First Embodiment

FIG. 1 is a longitudinal sectional view of a heat generating apparatusaccording to a first embodiment. FIG. 2 is a cross-sectional view of theheat generating apparatus according to the first embodiment. The heatgenerating apparatus illustrated in FIGS. 1 and 2 is mounted in a windelectric generating facility. The heat generating apparatus 1 accordingto the first embodiment includes a rotary shaft 3, a heat generator 4, aplurality of permanent magnets 5, and a magnet holder 6. The rotaryshaft 3 is rotatably supported by a fixed non-rotative body 2 via abearing 7.

The heat generator 4 is fixed to the rotary shaft 3. The heat generator4 includes a cylindrical member 4A that is coaxial with the rotary shaft3, and a disk-shaped connection member 4B connecting the cylindricalmember 4A and the rotary shaft 3. A plurality of through holes 4C aremade in the connection member 4B for weight saving and cooling. Themagnet holder 6 is disposed in the outer side of the heat generator 4,and it is fixed to the body 2. The magnet holder 6 includes acylindrical member 6 a that is coaxial with the rotary shaft 3. Thecylindrical member 6 a holds the magnets 5.

The magnets 5 are fixed on the inner peripheral surface of thecylindrical member 6 a so as to face the outer peripheral surface of theheat generator 4 (cylindrical member 4A) with a gap. As seen in FIG. 2,the magnets 5 are circumferentially arrayed across the wholecircumference. The magnetic poles (north pole and south pole) of each ofthe magnets 5 are radially arranged, and the magnetic pole arrangementsof circumferentially adjacent ones of the magnets 5 are opposite to eachother. In the first embodiment, the cylindrical member 6 a directlyholding the magnets 5 is made of a ferromagnetic material.

The heat generator 4, and especially the outer peripheral surface layerfacing the magnets 5 is made of a conductive material. As examples ofthe conductive material, ferromagnetic metal materials (for example,carbon steel, cast iron and the like), feebly magnetic metal materials(for example, ferritic stainless steel and the like), and non-magneticmetal materials (for example, aluminum alloys, austenitic stainlesssteel, copper alloys and the like) can be named.

A cylindrical partition wall 15 is disposed in the gap between the heatgenerator 4 and the magnets 5. The partition wall 15 is fixed to thebody 2 and defines a closed container surrounding the heat generator 4.The partition wall 15 is made of a non-magnetic material. This is toprevent the partition wall 15 from exerting adverse effects on themagnetic fields from the magnets 5 to the heat generator 4.

When the rotary shaft 3 rotates, the heat generator 4 rotate togetherwith the rotary shaft 3 (see the outlined arrow in FIG. 1). This causesa relative rotational speed difference between the magnets 5 and theheat generator 4. As shown in FIG. 2, the magnetic poles (north pole andsouth pole) of each of the magnets 5 facing the outer peripheral surfaceof the heat generator 4 are radially arranged, and the magnetic polearrangements of circumferentially adjacent ones of the magnets 5 areopposite to each other. The cylindrical member 6 a holding the magnets 5is ferromagnetic.

In the structure, the magnetic fluxes from the magnets 5 (the magneticfields of the magnets 5) are as follows. With regard to a first magnet 5and a second magnet 5 that are adjacent to each other, the magnetic fluxfrom the south pole of the first magnet 5 reaches the heat generator 4(cylindrical member 4A) facing the first magnet 5. The magnetic fluxthat has reached the heat generator 4 reaches the north pole of thesecond magnet 5. The magnetic flux from the south pole of the secondmagnet 5 reaches the north pole of the first magnet 5 via thecylindrical member Ga. Thus, the circumferentially adjacent magnets 5form a magnetic circuit across the adjacent magnets 5, the cylindricalmember 6 a holding the magnets 5, and the heat generator 4. Suchmagnetic circuits are formed over the entire circumference such thatadjacent magnetic fluxes are in opposite directions. Then, the magneticfields of the magnets 5 spread out, and the magnetic flux densityreaching the heat generator 4 becomes high.

In a state where there is a relative rotational speed difference betweenthe magnets 5 and the heat generator 4, the magnetic fields of themagnets 5 act on the heat generator 4, thereby generating eddy currentsalong the outer peripheral surface of the heat generator 4 (cylindricalmember 4A). Interactions between the eddy currents and the magnetic fluxdensity from the magnets 5 cause braking force acting on the heatgenerator 4, which is rotating together with the rotary shaft 3, in thereverse direction to the rotational direction, according to Fleming'sleft-hand rule.

The generation of eddy currents causes heat generation of the heatgenerator 4 along with the generation of braking force. As describedabove, the magnetic flux density reaching the heat generator 4 is high,and therefore, the eddy currents generated in the heat generator 4 bythe effects of magnetic fields from the magnets 5 are high, therebyresulting in achievement of sufficient heat generation.

The heat generating apparatus 1 includes a heat recovery system tocollect and utilize the heat generated in the heat generator 4. In thefirst embodiment, the heat recovery system includes an inlet 11 and anoutlet 12 made in the body 2, which defines the closed containertogether with the partition wall 15, and leading to the internal spaceof the closed container, that is, the space where the heat generator 4is located (the space hereinafter referred to as “heat generator lyingspace”). An inlet pipe and an outlet pipe, which are not shown in thedrawings, are connected to the inlet 11 and the outlet 12, respectively,of the heat generator lying space. The inlet pipe and the outlet pipeare connected to a heat storage device, which is not shown in thedrawings. The heat generator lying space (internal space of the closedcontainer), the inlet pipe, the outlet pipe and the heat storage deviceform a passage, and the heat medium flows and circulates in this passage(see the solid arrow in FIG. 1).

The heat generated in the heat generator 4 is transferred to the heatmedium flowing in the heat generator lying space. The heat medium in theheat generator lying space is discharged from the heat generator lyingspace through the outlet 12, and led to the heat storage device via theoutlet pipe. The heat storage device receives heat from the heat mediumby heat exchange, and stores the heat therein. The heat medium that haspassed through the heat storage device flows into the inlet pipe, andreturns to the heat generator lying space through the inlet 11. In thisway, the heat generated in the heat generator 4 is collected.

In the heat generating apparatus 1 according to the first embodiment, asdescribed above, since sufficient heat generation is achieved by theheat generator 4, it is possible to recover thermal energy from kineticenergy of the rotary shaft 3 efficiently. In the heat generatingapparatus 1, also, the heat generator 4 is held in the internal space ofa closed container. Thereby, it is possible to reduce the loss of thethermal energy generated by the heat generator 4.

The heat generating apparatus 1 according to the first embodiment may bemounted in a wind electric generating facility. For example, thepower-generating apparatus of the wind electric generating facility maybe replaced with the heat generating apparatus 1 according to the firstembodiment. In other words, as illustrated in FIG. 1, the propeller 20,which is a windmill, may be disposed on an extended line of the rotaryshaft 3 of the heat generating apparatus 1. The rotary shaft 21 of thepropeller 20 is rotatably supported by the fixed body 2 via a bearing25. The rotary shaft 21 of the propeller 20 is connected to the rotaryshaft 3 of the heat generating apparatus 1 via a clutch 23 and anaccelerator 24. Rotation of the rotary shaft 21 of the propeller 20 isaccompanied by rotation of the rotary shaft 3 of the heat generatingapparatus 1. In this regard, the rotational speed of the rotary shaft 3of the heat generating apparatus 1 is increased by the accelerator 24 tobecome higher than the rotational speed of the rotary shaft 21 of thepropeller 20. As the accelerator 24, for example, a planetary gearmechanism can be used.

In the wind electric generating facility, the propeller 20 receives windand rotates (see the outlined arrow in FIG. 1). The rotation of thepropeller 20 is accompanied by rotation of the rotary shaft 3 of theheat generating apparatus 1, whereby heat is generated in the heatgenerator 4, and the generated heat is stored in the heat storagedevice. Thus, the kinetic energy of the rotary shaft 3 of the heatgenerating apparatus 1 generated by rotation of the propeller 20 ispartly converted to thermal energy, and the thermal energy is collectedand stored. In this regard, between the propeller 20 and the heatgenerating apparatus 1, there is no such thing as the hydraulic pump orhydraulic motor provided in the wind electric generating facilitydisclosed in Patent Literature 1, and the energy conversion loss issmall. The heat stored in the heat storage device is utilized forelectric generation by use of a thermal element, a Stirling engine,etc., for example.

The rotation of the rotary shaft 3 of the heat generating apparatus 1causes generation of heat in the heat generator 4 and generation ofbraking force in the rotary shaft 3 to decelerate the rotation thereof.Thereby, the rotational speed of the propeller 20 is adjusted via theaccelerator 24 and the clutch 23. The clutch 23 has the followingfunctions. When heat generation in the heat generating apparatus 1 isneeded, the clutch 23 connects the rotary shaft 21 of the propeller 20to the rotary shaft 3 of the heat generating apparatus 1. Thereby, therotating force of the propeller 20 is transmitted to the heat generatingapparatus 1. When heat generation is no longer necessary because heat isstored in the heat storage device to capacity or when the heatgenerating apparatus 1 needs to be stopped for maintenance, the clutch23 disconnects the rotary shaft 21 of the propeller 20 from the rotaryshaft 3 of the heat generating apparatus 1. Thereby, the rotating forceof the propeller 20 is not transmitted to the heat generating apparatus1. In order to prevent the propeller 20 from rotating freely by wind onthe occasion, it is preferred that a brake system of a frictional type,an electromagnetic type or the like to stop the rotation of thepropeller 20 is provided between the propeller 20 and the clutch 23.

As described above, the eddy currents generated in the heat generator 4(cylindrical member 4A) cause heat generation in the heat generator 4.Therefore, the magnets 5 may rise in temperature by heat from the heatgenerator 4 (for example, radiant heat), thereby decreasing the magneticforce of the magnets 5. Therefore, it is preferred to take a measure toinhibit the temperature rise of the magnets 5.

In this regard, in the heat generating apparatus 1 according to thefirst embodiment, the heat generated in the heat generator 4 is blockedby the partition wall 15 of the closed container. Thereby, the magnets 5can be prevented from rising in temperature. In this case, it ispreferred that the space between the magnets 5 and the partition wall 15is filled with a heat insulating material or alternatively made vacuum.This ensures the blocking of the heat from the heat generator 4.

FIG. 3 is a cross-sectional view of a preferred example of a heatgenerator of the heat generating apparatus according to the firstembodiment. FIG. 3 is an enlarged view of the outer peripheral surfaceof the heat generator 4 (cylindrical member 4A) facing the magnets 5 andits adjacent area. As seen in FIG. 3, the heat generator 4 includes afirst layer 4 b, a second layer 4 c and an oxidation resistant coating 4d stacked in this order on the outer peripheral surface of a base 4 a.The base 4 a is made of a conductive metal material with highpyroconductivity (for example, a copper alloy, an aluminum alloy or thelike). The first layer 4 b is made of a ferromagnetic metal material(for example, carbon steel, cast iron or the like). The second layer 4 cis made of a non-magnetic or feebly magnetic metal material, and thematerial preferably has higher conductivity than the conductivity of thefirst layer 4 b (for example, an aluminum alloy, a copper alloy or thelike). The oxidation resistant coating 4 d is, for example, a Ni(nickel) plated layer.

Buffer layers 4 e are provided between the base 4 a and the first layer4 b, between the first layer 4 b and the second layer 4 c and betweenthe second layer 4 c and the oxidation resistant coating 4 d. Each ofthe buffer layers 4 e has a linear expansion coefficient that is greaterthan the linear expansion coefficient of one of its adjacent materialsand smaller than the linear expansion coefficient of the other of itsadjacent materials. This is for prevention of delamination. The bufferlayers 4 e are, for example, NiP (nickel-phosphorus) plated layers.

This layered structure increases the eddy currents generated in the heatgenerator 4 by the effects of magnetic fields from the magnets 5,thereby resulting in achievement of great braking force and sufficientheat generation. However, the second layer 4 c may be omitted, andfurther, the buffer layers 4 e may be omitted.

Second Embodiment

FIG. 4 is a cross-sectional view of a heat generating apparatusaccording to a second embodiment. The heat generating apparatus 1according to the second embodiment is based on the structure of the heatgenerating apparatus 1 according to the first embodiment. The sameapplies to the third and fourth embodiments which will be describedlater. The heat generating apparatus 1 according to the secondembodiment differs from the heat generating apparatus 1 according to thefirst embodiment principally in the way of arranging the magnets 5.

As shown in FIG. 4, the magnets 5 are circumferentially arrayed on theinner peripheral surface of the cylindrical member 6 a across the wholecircumference. The magnetic poles (north pole and south pole) of each ofthe magnets 5 are circumferentially arranged, and the magnetic polearrangements of circumferentially adjacent ones of the magnets 5 areopposite to each other. In the second embodiment, the cylindrical member6 a directly holding the magnets 5 is made of a non-magnetic material.Pole pieces made of a ferromagnetic material are provided between thecircumferentially arrayed magnets 5.

In the second embodiment, the magnetic fluxes from the magnets 5 (themagnetic fields of the magnets 5) are as follows. Circumferentiallyadjacent magnets 5 are arranged such that the magnetic poles thereofwith the same polarity face each other across a pole piece 9. Also, thecylindrical member 6 a holding the magnets 5 is non-magnetic. Therefore,the magnetic fluxes from the south poles of these magnets 5 repel eachother and reach the heat generator 4 (cylindrical member 4A) via thepole piece 9. The magnetic fluxes that have reached the heat generator 4reach the north poles of the respective magnets 5 via pole pieces 9respectively adjacent thereto. Thus, each of the magnets 5 forms amagnetic circuit across the magnet 5, the adjacent pole pieces 9 and theheat generator 4. Such magnetic circuits are formed over the entirecircumference such that adjacent magnetic fluxes are in oppositedirections. Then, the magnetic fields of the magnets 5 spread out, andthe magnetic flux density reaching the heat generator 4 becomes high.

Accordingly, the heat generating apparatus 1 according to the secondembodiment has the same effects as the heat generating apparatusaccording to the first embodiment.

Third Embodiment

FIG. 5 is a longitudinal sectional view of a heat generating apparatusaccording to a third embodiment. The heat generating apparatus 1according to the third embodiment differs from the heat generatingapparatus 1 according to the first embodiment principally in the way ofarranging the magnets 5.

As shown in FIG. 5, the magnets 5 are axially arrayed on the innerperipheral surface of the cylindrical member 6 a across the whole axiallength. The magnets 5 are cylindrical. The magnetic poles (north poleand south pole) of each of the magnets 5 are axially arranged such thatthe magnetic pole arrangements of axially adjacent ones of the magnets 5are opposite to each other. In the third embodiment, the cylindricalmember 6 a directly holding the magnets 5 is made of a non-magneticmaterial as with the second embodiment. Pole pieces 9 made of aferromagnetic material are provided between the axially arrayed magnets5. Further, pole pieces 9 are provided at both ends of the axial arrayof magnets 5.

In the third embodiment, the magnetic fluxes from the magnets 5 (themagnetic fields of the magnets 5) are as follows. Axially adjacentmagnets 5 are arranged such that the magnetic poles thereof with thesame magnetic polarity face each other across a pole piece 9. Also, thecylindrical member 6 a holding the magnets 5 is non-magnetic. Therefore,the magnetic fluxes from the south poles of these magnets 5 repel eachother and reach the heat generator 4 (cylindrical member 4A) via thepole piece 9. The magnetic fluxes that have reached the heat generator 4reach the north poles of the respective magnets 5 via pole pieces 9respectively adjacent thereto. Thus, each of the magnets 5 forms amagnetic circuit across the magnet 5, the adjacent pole pieces 9 and theheat generator 4. Such magnetic circuits are formed over the entireaxial length such that adjacent magnetic fluxes are in oppositedirections. Then, the magnetic fields of the magnets 5 spread out, andthe magnetic flux density reaching the heat generator 4 becomes high.

Accordingly, the heat generating apparatus 1 according to the thirdembodiment has the same effects as the heat generating apparatusaccording to the first embodiment.

Fourth Embodiment

FIG. 6 is a longitudinal sectional view of a heat generating apparatusaccording to a fourth embodiment. The heat generating apparatus 1according to the fourth embodiment is configured in light of inhibitionof temperature rise of the magnets 5, and includes a cooling system forcooling the magnets 5.

The cooling system of the heat generating apparatus 1 according to thesixth embodiment has the following structure as shown in FIG. 6. An airinlet 31 and an air outlet 32, which lead to the space where the magnets5 and the magnet holder 6 are located (the space being hereinafterreferred to as “magnets-lying space”), are made in the body 2. FIG. 6shows an example where the air outlet 32 pierces through the magnetholder 6 (cylindrical member 6 a).

An inlet pipe 33 and an outlet pipe 34 are connected to the air inlet 31and the air outlet 32, respectively, of the magnets-lying space. Theinlet pipe 33 and the outlet pipe 34 are connected to a heat exchanger35. The magnets-lying space, the inlet pipe 33, the outlet pipe 34 andthe heat exchanger 35 form a passage, and a cooling medium flows andcirculates in this passage (see the dotted arrows in FIG. 6). In thepassage, a pump 36 is provided to send the cooling medium.

In this structure, the cooling medium is introduced in the magnets-lyingspace through the inlet 31 by the operation of the pump 36 (see thedotted arrows in FIG. 6). The cooling medium introduced in themagnets-lying space flows around the magnets 5. Meanwhile, the magnets 5are cooled. The cooling medium that has cooled the magnets 5 isdischarged into the outlet pipe 34 through the outlet 32 (see the dottedarrows in FIG. 6). The cooling medium discharged into the outlet pipe 34is cooled in the heat exchanger 35 and then, sent to the inlet pipe 33.In this way, the magnets 5 are forcibly cooled, thereby inhibiting thetemperature rise of the magnets 5.

This magnet cooling system is applicable to any other heat generatingapparatus according to the present invention. For example, the magnetcooling system is applicable to the heat generating apparatusesaccording to the first, second and third embodiments. Also, the magnetcooling system is applicable to a heat generating apparatus including adisk-shaped heat generator, which will be described later.

According to a modification of the fourth embodiment, the inlet pipe 33,the outlet pipe 34, the heat exchanger 35 and the pump 36 may beomitted. In this case, external air can be introduced in themagnet-lying space through the air inlet 31 and discharged through theair outlet 32 by a blower or the like. Thereby, the magnets 5 are cooledby the air flowing in the magnet-lying space.

The present invention is not limited to the above-described embodiments,and it is possible to carry out the present invention by appropriatelymodifying the above-described embodiments without departing from thespirit and scope thereof. For example, in the above-describedembodiments, the heat generator 4 is cylindrical, but the heat generator4 may be shaped like a disk that is coaxial with the rotary shaft 3. Inthis case, the magnet holder 6 is shaped like a disk that is coaxialwith the rotary shaft 3. The disk-shaped member faces a principalsurface (one of the surfaces on both sides in the axial direction) ofthe disk-shaped heat generator, and the disk-shaped member holds themagnets 5 on its surface facing the principal surface of the heatgenerator. Accordingly, the magnets face the principal surface of theheat generator with a gap. In this case, there are possible three waysof arranging the magnets 5 as follows.

A first way of arrangement is based on the magnet arrangement in thefirst embodiment. In the first way of arrangement, the magnets arecircumferentially arrayed across the whole circumference. The magneticpoles (north pole and south pole) of each of the magnets are axiallyarranged, and the magnetic pole arrangements of circumferentiallyadjacent ones of the magnets are opposite to each other. In this case,the disk-shaped member directly holding the magnets is made of aferromagnetic material.

A second way of arrangement is based on the magnet arrangement in thesecond embodiment. In the second way of arrangement, the magnets arecircumferentially arrayed across the whole circumference. The magneticpoles (north pole and south pole) of each of the magnets arecircumferentially arranged, and the magnetic pole arrangements ofcircumferentially adjacent ones of the magnets are opposite to eachother. In this case, the disk-shaped member directly holding the magnetsis made of a non-magnetic material. Pole pieces made of a ferromagneticmaterial are provided between the circumferentially arrayed magnets.

A third way of arrangement is based on the magnet arrangement in thethird embodiment. In the third way of arrangement, the magnets arering-shaped, and the ring-shaped magnets are coaxially arrayed in theradial direction. The magnetic poles (north pole and south pole) of eachof the magnets are radially arranged, and the magnetic pole arrangementsof radially adjacent ones of the magnets are opposite to each other. Inthis case, the disk-shaped member directly holding the magnets is madeof a non-magnetic material. Pole pieces made of a ferromagnetic materialare provided between the radially arrayed magnets. Additionally, polemagnets are provided at both ends of the radial array of magnets.

The heat generating apparatuses described above can be mounted not onlyin wind electric generating facilities but also in hydroelectricgenerating facilities and other power-generating facilities utilizingkinetic energy of a fluid.

Further, the heat generating apparatuses described above can be mountedin vehicles (for example, trucks, buses and the like). In such a case,any of the heat generating apparatuses may be provided in a vehicle as acomponent separate from an eddy current decelerator serving as anauxiliary brake or alternatively may be provided in a vehicle to doubleas an auxiliary brake. In a case where any of the heat generatingapparatuses doubles as an auxiliary brake, a switch mechanism shall beprovided for switching between braking and non-braking. When any of theheat generating apparatuses is used as an auxiliary brake (decelerator),the apparatus reduces the rotational speeds of the rotary shafts such asthe propeller shaft, the drive shaft and the like. Thereby, the runningspeed of the vehicle is controlled. In this regard, along with thegeneration of braking force to reduce the rotational speeds of therotary shafts, heat is generated. The heat recovered by the heatgenerating apparatus mounted in the vehicle is utilized, for example, asa heat source for a heater for heating the inside of the vehicle or as aheat source for a refrigerator for refrigerating the inside of acontainer.

INDUSTRIAL APPLICABILITY

The eddy current heat generating apparatuses according to the presentinvention can be effectively employed in power-generating facilitiesutilizing kinetic energy of a fluid, such as wind electric generatingfacilities, hydroelectric generating facilities and the like, and invehicles, such as trucks, busses and the like.

REFERENCE SYMBOLS

1: eddy current heat generating apparatus

2: body

3: rotary shaft

4: heat generator

4A: cylindrical member

4B: connection member

4C: through hole

4 a: base

4 b: first layer

4 c: second layer

4 d: oxidation resistant coating

4 e: buffer layer

5: permanent magnet

6: magnet holder

6 a: cylindrical member

7: bearing

8: cover

9: pole piece

11: inlet

12: outlet

15: partition wall

20: propeller

21: rotary shaft

22: brake system

23: clutch

24: accelerator

25: bearing

31: air inlet

32: air outlet

33: inlet pipe

34: outlet pipe

35: heat exchanger

36: pump

1. An eddy current heat generating apparatus comprising: a rotary shaftrotatably supported by a non-rotative member; a heat generator fixed tothe rotary shaft; a plurality of permanent magnets arrayed to face theheat generator with a gap such that magnetic pole arrangements ofadjacent ones of the permanent magnets are opposite to each other; amagnet holder holding the permanent magnets and fixed to thenon-rotative member; and a heat recovery system collecting heatgenerated in the heat generator.
 2. The eddy current heat generatingapparatus according to claim 1, wherein the heat recovery systemincludes: a closed container fixed to the non-rotative member andsurrounding the heat generator, the closed container including apartition wall disposed in the gap between the heat generator and thepermanent magnets; pipes connected to an inlet and an outlet,respectively, which lead to an internal space of the closed container; aheat storage device connected to the pipes; and a heat mediumcirculating in the closed container, the pipes and the heat storagedevice.
 3. The eddy current heat generating apparatus according to claim2, wherein a space between the permanent magnets and the partition wallis filled with a heat insulating material or alternatively is madevacuum.
 4. The eddy current heat generating apparatus according to claim1, further comprising a cooling system configured to cool the permanentmagnets.
 5. The eddy current heat generating apparatus according toclaim 1, wherein: the heat generator is cylindrical; and the permanentmagnets are circumferentially arrayed to face a whole circumference ofan outer peripheral surface of the heat generator such that magneticpoles of each of the permanent magnets are radially arranged and suchthat the magnetic pole arrangements of adjacent ones of thecircumferentially arrayed permanent magnets are opposite to each other.6. The eddy current heat generating apparatus according to claim 5,wherein: the magnet holder includes a cylindrical member holding thepermanent magnets on its inner peripheral surface; and the cylindricalmember is ferromagnetic.
 7. The eddy current heat generating apparatusaccording to claim 1, wherein: the heat generator is cylindrical; andthe permanent magnets are circumferentially arrayed to face a wholecircumference of an outer peripheral surface of the heat generator suchthat magnetic poles of each of the permanent magnets arecircumferentially arranged and such that the magnetic pole arrangementsof adjacent ones of the circumferentially arrayed permanent magnets areopposite to each other.
 8. The eddy current heat generating apparatusaccording to claim 7, wherein: the magnet holder includes a cylindricalmember holding the permanent magnets on its inner peripheral surface;and the cylindrical member is non-magnetic, and pole pieces are providedbetween the circumferentially arrayed permanent magnets.
 9. The eddycurrent heat generating apparatus according to claim 1, wherein: theheat generator is cylindrical; and the permanent magnets are axiallyarrayed to face a whole axial length of an outer peripheral surface ofthe heat generator such that magnetic poles of each of the permanentmagnets are axially arranged and such that the magnetic polearrangements of adjacent ones of the axially arrayed permanent magnetsare opposite to each other.
 10. The eddy current heat generatingapparatus according to claim 9, wherein: the magnet holder includes acylindrical member holding the permanent magnets on its inner peripheralsurface; and the cylindrical member is non-magnetic, and pole pieces areprovided between the axially arrayed permanent magnets and at both endsof the axial array of permanent magnets.
 11. The eddy current heatgenerating apparatus according to claim 1, wherein: the heat generatoris disk-shaped; and the permanent magnets are circumferentially arrayedto face a whole circumference of a principal surface of the heatgenerator such that magnetic poles of each of the permanent magnets areaxially arranged and such that the magnetic pole arrangements ofadjacent ones of the circumferentially arrayed permanent magnets areopposite to each other.
 12. The eddy current heat generating apparatusaccording to claim 11, wherein: the magnet holder includes a disk-shapedmember holding the permanent magnets on its surface facing the principalsurface of the heat generator; and the disk-shaped member isferromagnetic.
 13. The eddy current heat generating apparatus accordingto claim 1, wherein: the heat generator is disk-shaped; and thepermanent magnets are circumferentially arrayed to face a wholecircumference of a principal surface of the heat generator such thatmagnetic poles of each of the permanent magnets are circumferentiallyarranged and such that the magnetic pole arrangements of adjacent onesof the circumferentially arrayed permanent magnets are opposite to eachother.
 14. The eddy current heat generating apparatus according to claim13, wherein: the magnet holder includes a disk-shaped member holding thepermanent magnets on its surface facing the principal surface of theheat generator; and the disk-shaped member is non-magnetic, and polepieces are provided between the circumferentially arrayed permanentmagnets.
 15. The eddy current heat generating apparatus according toclaim 1, wherein: the heat generator is disk-shaped; and the permanentmagnets are radially arrayed to face a whole radius of a principalsurface of the heat generator such that magnetic poles of each of thepermanent magnets are radially arranged and such that the magnetic polearrangements of adjacent ones of the radially arrayed permanent magnetsare opposite to each other.
 16. The eddy current heat generatingapparatus according to claim 15, wherein: the magnet holder includes adisk-shaped member holding the permanent magnets on its surface facingthe principal surface of the heat generator; and the disk-shaped memberis non-magnetic, and pole pieces are provided between the radiallyarrayed permanent magnets and at both ends of the radial array ofpermanent magnets.
 17. The eddy current heat generating apparatusaccording to claim 1, wherein: the heat generator is made of one or morekinds of conductive magnetic materials.
 18. The eddy current heatgenerating apparatus according to claim 1, wherein: the heat generatoris made of at least a conductive ferromagnetic material and a conductivenon-magnetic material, the conductive non-magnetic material lying closeto the permanent magnets.